A conventional printer performs printing on a label. A plurality of labels, which is a piece of paper having an adhesion layer on a surface opposite to a printing surface, adheres to a belt-like mount at substantially fixed intervals (gaps), and a label roll obtained by winding the mount attached with labels is placed in a paper feed section of the printer.
The printing surface of the label and the mount alternatively appear at a printing position of the printer during conveyance of a label roll. The printer needs to confirm the position of the label on the label roll to perform printing at a correct position. For example, an optical sensor is used to confirm the position of the label. The printer determines a boundary between the label and the gap from an increase and/or decrease in an amount of light (amount of transmitted light) penetrating the label and/or the mount.
However, there are often perforations at a portion between adjacent labels on the mount. The perforations are continuous small holes formed on the mount to make subsequent separation of labels easy. In the printer which confirms the position of the label by the above method, when a label roll having perforations is used, since the amount of transmitted light is low at the perforation, there is a case in which the position of a perforation is mistaken as the boundary between the gap and the label. In this case, since the printer recognizes the position of the label erroneously, the accuracy of the printing position is low.